Radio wave propagation studies through modern windows

Abstract. It is a growing trend in the modern housing construction especially in northern parts of Europe and America to use modern windows with selective glasses in order to achieve the adequate thermal isolation. The idea is to conserve the energy and discourage the excess use of it following the guidelines of European commission, which aims to achieve zero energy buildings by 2020. Even though the use of such windows do address the energy issue at hand, but on the other hand they cause problems to the radio wave propagation through these windows. The reason for this is the use of metallic coating made of titanium oxide or silver oxide in general on these windows because of their good properties to provide thermal isolation, but are susceptible to deterioration of radio wave propagation through them. Various solutions to this problem have been addressed in this thesis along with their tradeoffs. The previous and current research being carried out to address this issue also have been discussed thoroughly including the research that worked as the motivation to pursue this issue. Amongst others, one solution is the use of passive repeater to achieve the power gain which have been focused on. A prototype repeater antenna developed earlier at CWC and tested through measurements addresses the problem considerably well. Measurements were taken at EMC chamber, University of Oulu, within the frequency range of 700 MHz to 10 GHz, and the results have been compared and analyzed in this thesis. According to our findings, the repeater antenna under the test has shown promising results. In the future work, the proposed repeater can be tested in real life scenarios and its performance can be analyzed within the real life environmental constraints

Corporate Dividend Policies during the COVID-19 Pandemic

: In this paper, we examine the changes in corporate dividend policies during the COVID-19 shock. For empirical analysis, we employ annual data of 360 companies from the Pakistan Stock Exchange over the period 2015–2020. Using descriptive analysis and Logit regression models, we find that firms were more likely to either omit or reduce dividend payments during the pandemic year of 2020 as compared to the trends in pre-COVID-19 years of 2015–2019. Further, firms with higher profitability, asset turnover and size were less likely to opt for dividend omissions. On the contrary, dividend omissions were more likely among firms with higher debt ratios. The findings of this study helps to understand firm dividend policies during crisis periods

Synthesis and Bio-Spectral Studies of Co(II) Complex of 5-Chloro-2,4-Dihydroxy Butyrophenoneoxime (CDHBOX)

Co(II) complex of 5-chloro-2,4-dihydroxy butyrophenoneoxime (CDHBOX) was synthesized from 5-chloro-2,4-dihydroxy butyrophenoneoxime by using standard protocol, and characterized by elemental analyses, melting point determination and spectral data. The ML2 (metal/ligand) stoichiometry of the complex was determined by spectrophotometric and potentiometric studies, and mass spectral data. The value of stability constant of the complex was found to be 6.94x 108 while its standard free energy of formation is 12.155 kcal/mol at 27ºC. Beer’s law is obeyed in the concentration range 2-15 ppm of Co. The value of molar extinction coefficient and sensitivity as per Sandell’s scale were found to 3.35x 103 L.mol-1cm-1and 0.017 μg Co/cm2 respectively. The value of activation energy and the Arrhenius constant Arrhenius constant were found as 4.949 kjmol-1, 74.39. The IR studies reveal that the phenolic proton is lost on complexation and the oxygen of the phenolic (–OH) and nitrogen of the oximino (=NOH) groups coordinate with Co(II) ion. The electronic spectra and magnetic susceptibility measurement indicate that the complex is paramagnetic and tetrahedral in nature. The antimicrobial activity of different concentrations of ligand and its Co(II)-complex  has been evaluated against Curvularia lunata, Fusarium oxysporum and Alternaria alternata fungi  and Streproproteus, Staph, Escherchia coli, Klebsella, and pseudomonas bacteria. The results indicated that the ligand (CDHBOX) and its Co(II) complex have good anti-microbial properties.Â

Leader-Follower Formation Control for Underwater Transportation using Multiple Autonomous Underwater Vehicles

The successful ability to conduct underwater transportation using multiple autonomous underwater vehicles (AUVs) is important for the commercial sector to undertake precise underwater installations on large modules, whilst for the military sector it has the added advantage of improved secrecy for clandestine operations. The technical requirements are the stability of the payload and internal collision avoidance while keeping track of the desired trajectory considering the underwater effects. Here, a leader-follower formation control strategy was developed and implemented on the transportation system of AUVs. PID controllers were used for the vehicles and a linear feedback controller for maintaining the formation. A Kalman Filter (KF) was designed to estimate the full state of the leader under disturbance, noise and limited sensor readings. The results demonstrate that though the technical requirements are met, the thrust oscillations under disturbance and noise produce the undesired heading angles

Assessment of Collision Avoidance Strategies for an Underwater Transportation System

Transportation using multiple autonomous vehicles with detection avoidance capability is useful for military applications. It is important for such systems to avoid collisions with underwater obstacles in an effective way, while keeping track of the target location. In this paper, sensor-based and path-planning methods of external collision avoidance were investigated for an underwater transportation system. In particular, sensor-based wall-following and hard-switching collision avoidance strategies and an offline RRT* path-planning method was implemented on the simulation model of the transportation system of four Hovering Autonomous Underwater Vehicles (HAUVs). Time-domain motion simulations were performed with each method and their ability to avoid obstacles was compared. The hard-switching method resulted in high yaw moments which caused the vehicle to travel towards the goal by a longer distance. Conversely, in the wall-following method, the yaw moment was kept to zero. Moreover, the wall-following method was found to be better than the hard-switching method in terms of time and power efficiency. The comparison between the offline RRT* path-planning and wall-following methods showed that the fuel efficiency of the former is higher whilst its time efficiency is poorer. The major drawback of RRT* is that it can only avoid the previously known obstacles. In future, offline RRT* and wall following can be blended for a better solution. The outcome of this paper provides guidance for the selection of the most appropriate method for collision avoidance for an underwater transportation system

Optimization of growth parameters for lipase production by Ganoderma lucidum using response surface methodology

Lipases comprise a group of hydrolytic enzymes which catalyze reversibly the hydrolysis and synthesis of triacylglycerides in the oil water interface. In this study, a response surface approach was used to study the production of extracellular lipase from Ganoderma lucidum which has diverse applications in various fields. Interactions were studied for five different variables (moisture, canola oil cake, olive oil, pH and time of incubation) which were found influential for lipase production. Using the statistical approach (response surface methodology), the maximum yield of lipase (4838 U/gds) by G. lucidum was observed under optimum conditions. The optimum values of these parameters were as follows: canola oil cake (12.50 g), moisture level (60%), pH (4.5), olive oil as inducer (2.0%) and incubation period (96 h) at 30°C. Exploration of fungal diversity for improved production of lipases using statistical models makes it a high-profile area for novel discovery with enormous potential of massive returns.Key words: Lipases, Ganoderma lucidum, statistical approach, solid state fermentation, incubation period, canola oil cake